/* 
 * Copyright (c) 2008 Knightsoft
 *
 * Licensed under the Apache License, Version 2.0 (the "License");
 * you may not use this file except in compliance with the License.
 * You may obtain a copy of the License at
 *
 *   http://www.apache.org/licenses/LICENSE-2.0
 *
 * Unless required by applicable law or agreed to in writing, software
 * distributed under the License is distributed on an "AS IS" BASIS,
 * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
 * See the License for the specific language governing permissions and
 * limitations under the License.
*/
package com.knightsoft.util;

import java.util.HashSet;
import java.util.Set;

/**
 * 
 * @version V1.0 Nov 10, 2008
 * @author Michael
 */
public class Sets {
	public static <T> Set<T> union(Set<T> a, Set<T> b) {
		Set<T> result = new HashSet<T>(a);
		result.addAll(b);
		return result;
	}

	public static <T> Set<T> intersection(Set<T> a, Set<T> b) {
		Set<T> result = new HashSet<T>(a);
		result.retainAll(b);
		return result;
	}

	// Subtract subset from superset:
	public static <T> Set<T> difference(Set<T> superset, Set<T> subset) {
		Set<T> result = new HashSet<T>(superset);
		result.removeAll(subset);
		return result;
	}

	// Reflexive--everything not in the intersection:
	public static <T> Set<T> complement(Set<T> a, Set<T> b) {
		return difference(union(a, b), intersection(a, b));
	}
}
